Millennial-scale periodicities associated with changes in wind ansd precipitation over the last glacial cycle (ca. 117 ± 8.5 ka BP) recorded in sediments from Lake Kai Iwi, Northland, New Zealand
No Thumbnail Available
Date
2022-01
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B. V.
Abstract
Mid-latitude Southern Hemisphere proxy records of changing environment, especially those that demonstrate past variability of the South Westerly Winds (SWW), are poorly-constrained prior to the Last Glacial Interglacial Transition (LGIT; ca. 14–11.7 ka BP) and are typically located far enough south or north that they often do not reflect both tropical and SWW signals. With this deficiency in mind, we present a ca. 117 ± 8.5 ka BP lake sediment record from Lake Kai Iwi, Northland, New Zealand (~36°S), located at a latitude that demonstrates changes in precipitation associated with both the northward expansion of the SWW belt and from tropical El Niño Southern Oscillation (ENSO) variability. We converted Lake Kai Iwi μ-XRF proxy data to even time-steps in order to apply Morelet wavelet analysis for identification of millennial-scale periodicities in the data that were likely driven by orbital forcing. The results indicate that Lake Kai Iwi records a ~1 ka periodicity possibly associated with Northern Hemisphere ice sheet dynamics; a ~2–4 ka periodicity associated with ~2.4 ka Hallstatt solar cycles, and a ~9 ka periodicity linked to CO2 outgassing from upwelling in the Southern Ocean driven by changes in intensity and position of the SWW. © 2021 Elsevier B.V.
Description
Keywords
Data, Southern Oscillation, Southern Hemisphere, Carbon dioxide, Wind, Glaciers, Solar cycle, Upwelling, Wave forces
Citation
Evans, G., Augustinus, P., Gadd, P., Zawadzki, A., Ditchfield, A., & Hopkins, J. (2022). Millennial-scale periodicities associated with changes in wind ansd precipitation over the last glacial cycle (ca. 117 ± 8.5 ka BP) recorded in sediments from Lake Kai Iwi, Northland, New Zealand. Global and Planetary Change, 208, 103688. doi:10.1016/j.gloplacha.2021.103688